Skull Base Surgery of the Posterior Fossa

129

Aggressive resection is contraindicated for
meningiomas located at the posterior tentorial region
invading the sinus partially with sinus patency [ 5 ].
After a conservative approach, the residual tumor
may be observed or stereotactically irradiated either
initially or at the time of recurrence [ 6 ].
In the case of total sinus occlusion, particularly
if collateral venous channels have developed,
complete removal of the tumor, including the seg-
ment of the invaded sinus, can be performed
safely without venous flow restoration [ 7 ].
An aggressive removal may be needed for a
higher-grade meningioma with reconstruction of
the sinus, especially in younger patients [ 4 ].

Illustrative Case

Case 8: Suboccipital Approach

with Resection of Invasion

into the Transverse Sinus (Fig. 9.10)

A 67-year-old woman presented with head-

ache. MR imaging demonstrated a mass lesion

at the right posterior tentorium, invading the

right transverse sinus. MR venography showed

the already occluded right transverse sinus.

The tumor was removed, including the part

invading the right transverse sinus, via a sub-

occipital approach. Postoperatively, there were

no complications.

Fig. 9.9 Case 7. Preoperative axial (a) and coronal (b)
T1-weighted magnetic resonance images with gadolinium
showing the lateral type of tentorial meningioma.
Preoperative CT venography shows occlusion of the right
sigmoid sinus (c). Postoperative axial (d) and coronal (e)
T1-weighted magnetic resonance images with gadolinium
show total resection of the tumor via a combined presig-
moid and retrosigmoid approach. Right temporal craniotomy

and suboccipital craniotomy with partial petrosectomy is

performed (f). After internal debulking of the tumor though

a retrosigmoid approach (g), the right sigmoid sinus is cut

at the distal side (h). Additional resection of the tumor into

the right sigmoid sinus is performed via a presigmoid

approach (i). The right transverse sinus is cut on the margin

of the tumor (j), and the tentorium is resected through a

presigmoid approach (k). The tumor is totally removed (l)

9 Tentorial Meningiomas